1. Field of the Invention
The present invention relates to a feedstuff for ruminants. It particularly relates to a granular feedstuff for ruminants which contains a protective material in the form of a calcium salt of mixed fatty acids.
2. Description of Related Art
It is known that additive agents such as amino acids and vitamins have been added to ruminant feedstuff for oral administration due to the high efficient absorption of the amino acids and vitamins in the abomasum. The art has also developed techniques for bypassing the rumen with such additives.
Heretofore, in oral administration of the feed additives, it has been proposed that the additives be dispersed into protective materials. The protective materials are stable in the gastric juices of the rumen and easily broken down in the abomasum. Known protective materials include higher fatty acids, triglycerides of the fatty acids, fats and oils, and hardened animal and plant oils. Various types of preparations coated by protective materials are described in Japanese Patent Laid-open No. 154956/1981 and in Japanese Patent Laid-open No. 151133/1986.
The present inventors have heretofore proposed preparations wherein active substances such as chitosan as the additive are dispersed into protective materials or the additive is coated with the protective material. These prior preparations are described in Japanese Laid-open No. 175449/1983 and in Japanese Patent Laid-open No. 198946/1984 and marketed under the tradename LACTET.RTM..
In addition, feedstuff preparations designed to bypass the rumen of ruminants are described in U.S. Pat. No. 4,826,694 and in U.S. Pat. No. 4,642,317. In general, these references describe preparations which comprise divalent metallic salts such as calcium or magnesium salts of fatty acids having 14, 16 and/or 18 carbon atoms.
Japanese Laid-open patent No. 313546/1988 describes a manufacturing method for preparing a feedstuff for ruminants wherein the protective material is a calcium salt of mixed fatty acids obtained from naturally occurring fat and oils. The additive substance is heated and softened at a temperature above its melting point. The resulting mixture is then solidified by cooling and then granulated.
It has been observed that the protective material prepared by known methods, when orally administered to ruminants, display excellent rumen bypass properties and excellent digestive/absorption properties in the abomasum. However, these same materials have poor storage stability above 40.degree. C. due to the low softening point of the protective materials.
The poor heat stability properties of the feedstuff pellets was partially solved by using a protective material comprising metallic salts of mixed fatty acids having a softening point of at least 100.degree. C. However, in the preparations described in the references, the active substance or additive cannot be sufficiently protected by a coating of the metallic salt of mixed fatty acids. The results were widely varying rumen bypass properties and consequently, these materials were insufficient for the intended purpose of oral administration of the active substances.
It is, therefore, an object of the present invention to provide a granular ruminant feedstuff in which the active substance is dispersed in or coated with a calcium salt of fatty acids and which has excellent heat stability, excellent rumen bypass properties and excellent digestive/absorption properties in the abomasum and intestines when orally administered to a ruminant.